mainlining shenanigans
bfe8cc1db0
Alexander reported a syzkaller / KASAN finding on s390, see below for complete output. In do_huge_pmd_anonymous_page(), the pre-allocated pagetable will be freed in some cases. In the case of userfaultfd_missing(), this will happen after calling handle_userfault(), which might have released the mmap_lock. Therefore, the following pte_free(vma->vm_mm, pgtable) will access an unstable vma->vm_mm, which could have been freed or re-used already. For all architectures other than s390 this will go w/o any negative impact, because pte_free() simply frees the page and ignores the passed-in mm. The implementation for SPARC32 would also access mm->page_table_lock for pte_free(), but there is no THP support in SPARC32, so the buggy code path will not be used there. For s390, the mm->context.pgtable_list is being used to maintain the 2K pagetable fragments, and operating on an already freed or even re-used mm could result in various more or less subtle bugs due to list / pagetable corruption. Fix this by calling pte_free() before handle_userfault(), similar to how it is already done in __do_huge_pmd_anonymous_page() for the WRITE / non-huge_zero_page case. Commit |
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| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.